The Ministry of Intelligence and Security (MOIS, also known as Vezarat-e Ettela'at va Amniat-e Keshvar or VEVAK) was created after the SAVAMA, the Ministry of Information and Security, the first post-revolution intelligence and security group that took over after SAVAK, the intelligence service of Imperial Iran, was dissolved by Ayatollah Khomeini in 1979. SAVAMA was officially created by the Majlis in 1984 and was lead by Major General Fardust, who was arrested in December 1985 under charges of being a Soviet informer. To head the MIOS a prospective minister must secure 50% plus one votes of the Majalis and must be a cleric. For unclear reasons the name SAVAMA was quickly replaced with VEVAK.

With a large budget and extensive organization, the MOIS is of the most powerful ministries in the Iranian government. The ministry has traditionally operated under the guidance of the Velayat-e Faqih apparatus of Ali Khamenei and answers directly to the Supreme Leader. The group has a secret budget making it very difficult to discern how large the Ministry's operations are and to what end they are intended.

The MOIS's original charter stated the organization was in charge of "gathering, procurement, analysis, and classification of necessary information inside and outside the country," but it also "plays the lead role in organizing and conducting terrorist operations abroad, and it runs operations out of Iranian embassies, consulates, and Islamic centers overseas." From that original declaration the group has had a range of duties to the Iran, all of which dealt with the security of the government against threats both domestic and abroad that might seek to destabilize it. Along with the MOIS, the Islamic Revolution Guards Corps, the Basij Resistance Forces, the Ansar-i Hezbullah, and the Law Enforcement Forces work together for domestic security.

The MOIS reportedly operated various prisons and prison wings throughout Iran, which did not require the Iranian government's oversight. The most famous of these facilities was referred to as Section 209 of the Evin House of Detention in Tehran, the former prison used by the SAVAK. Section 209 was said to hold those the Iranian Government deemed national security threats, often believed to be political prisoners.

The MOIS had been known to work with the Ministry of Islamic Culture and Guidance to help censor news reports of the arrests and trials of student political activists. Reporters have often accused the Ministry of harassing them so that they would not report on issues like the nuclear program and not to write articles that are critical to the regime.

The Department of Disinformation, said to be the largest department in MOIS, was in charge of creating faulty information about Iranian opponents and disseminating. The section had a staff of several thousand, many of whom are former dissidents who had either been forced or lured by the great deals of money, to work with the organization. During the Presidency of Ahmadinejad the Foreign Affairs directorate received an increasingly large amount of attention and growth.

MOIS personnel were often either attached as diplomats in Iranian embassies and consulate offices or as Ministry of Guidance and Propaganda representatives. MOIS members have used embassies as listening posts and locations where terrorists were recruited and attacks were planed. Prospective members of the ministry were taken from Iran's security bureaucracies and vetted by agents. To prove their loyalty they reportedly often had to kill and torture dissidents. Non-official covers included Iran Air (the official airline of Iran) or as students, merchants, mechanics, shopkeepers, bank clerks, as well as members of opposition groups. VEVAK frequently relied on the foreign branches of Iranian state-controlled banks to place intelligence agents and to finance terrorist operations. In Germany, for instance, the most prominent was Bank Melli (eventually designated as an entity supporting proliferation activities by the United States and members of the European Union), which maintained branches in Hamburg, Frankfurt, and Dusseldorf. On occasion there were reportedly purges of MOIS employees, where certain individuals who had fallen out of favor would die of mysterious circumstances or "commit suicide."